Bactericidal Antibody Responses Elicited by a Meningococcal Outer Membrane Vesicle Vaccine with Overexpressed Factor H–Binding Protein and Genetically Attenuated Endotoxin

Abstract

Background Outer membrane vesicle (OMV) vaccines from mutant N. meningitidis strains engineered to over-express factor H-binding protein (fHbp) elicited broadly protective serum antibody responses in mice. The vaccines investigated were not treated with detergents to avoid extracting fHbp, which is a lipoprotein. Because of their high endotoxin content, the vaccines would not be safe to administer to humans. Methods We prepared a native OMV vaccine from a strain engineered to over-express fHbp and in which the gene encoding LpxL1 was inactivated, which reportedly decreased endotoxin activity. Results The OMV vaccine from the mutant had similar or lower ability to induce proinflammatory cytokines by human peripheral blood mononuclear cells as a detergent-extracted wildtype OMV, and 1000- to 10,000-fold lower activity than a native wildtype OMV. In mice, the OMV vaccine from the mutant elicited higher serum bactericidal antibody responses against a panel of heterologous N. meningitidis strains than a control multicomponent recombinant protein vaccine, or a detergent-extracted OMV vaccine that previously had been demonstrated to confer protection against meningococcal disease in humans. Conclusions The data illustrate the potential to develop a broadly immunogenic native OMV vaccine with decreased endotoxin activity that is potentially suitable for testing in humans.

A Critical Threshold of Meningococcal Factor H Binding Protein Expression Is Required for Increased Breadth of Protective Antibodies Elicited by Native Outer Membrane Vesicle Vaccines

“…The protein concentration was measured with the bicinchoninic acid (BCA) protein assay kit (Thermo Scientific, Rockford, IL). The major proteins in the NOMVs were assessed by SDS-PAGE with Coomassie blue staining (25). Selected bands were cut from the gels and identified by mass spectrometry (11).…”

Impaired Immunogenicity of Meningococcal Neisserial Surface Protein A in Human Complement Factor H Transgenic Mice

“…For a vaccine intended for use in humans, the expression of NspA in N. meningitidis is more likely to retain native folding and important epitopes for eliciting bactericidal antibodies than the expression of a purified recombinant NspA in E. coli (14). Thus, it should be possible to prepare a meningococcal NOMV-NspA vaccine from a mutant N. meningitidis strain with a genetically attenuated endotoxin and overexpressed NspA by methods similar to those used to prepare meningococcal NOMV vaccines with overexpressed FHbp (27,32,33) which are intended for use in humans.…”

“…As described above, to determine whether the impaired anti-NspA bactericidal antibody responses of the human FH transgenic mice were specific for NspA, we immunized groups of wild-type and human FH transgenic mice with a control meningococcal NOMV vaccine with overexpressed mutant R41S FHbp that had low levels of FH binding (11,26). Based on previous data, we expected that most of the serum bactericidal antibody would be directed at subfamily B FHbp (16) or PorA P1.5,2 (26,27). Figure 5 shows the serum bactericidal titers of antibodies against BZ198 measured in individual wild-type and human FH transgenic mice immunized with the meningococcal NOMV vaccine (Fig.…”

Current Trends In Research, Development And Production Of Prophylactic Vaccines: Report of Vaccipharma 2015 Congress

“…Issues to be studied more carefully are duration of protection in various age groups, mucosal immunity and herd protection. Of particular note, a substantial difference in immunogenicity has been observed with recombinant fHbp versus the experimental formulations of native OMV vaccines where fHbp has been included as over-expressed vaccine antigen (NOMV-OEfHbp with 3-6 times the ordinary level found in wild type strains) [89][90][91]. The total amount of fHbp in the two formulations can be more than 100 times different, and the NOMV formulation induces better anti-fHbp immunity than the recombinant vaccine.…”

“…Since fHbp is a membrane-attached lipoprotein the NOMV must be manufactured without using the standard detergent extraction established for manufacture of ordinary OMV vaccines [92]. Instead the vaccine can be made tolerable for humans with genetic manipulation of LPS (lpx1-mutants) [89]. Preclinical studies with NOMV vaccines have shown higher protective titres and broader immune responses, resulting in better capacity to kill strains with fHbp variants that are substantially different from the vaccine antigen selected for the vaccine [91,[93][94][95].…”